 /*******************************************************************************
  * Copyright (c) 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  ******************************************************************************/

 package org.eclipse.ui.internal.navigator.filters;

 import org.eclipse.core.expressions.EvaluationContext;
 import org.eclipse.core.expressions.EvaluationResult;
 import org.eclipse.core.expressions.Expression;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.jface.viewers.Viewer;
 import org.eclipse.jface.viewers.ViewerFilter;
 import org.eclipse.ui.internal.navigator.NavigatorPlugin;

 /**
  * @since 3.2
  *
  */
 public class CoreExpressionFilter extends ViewerFilter {

     private Expression filterExpression;

     /**
      * Creates a filter which hides all elements that match the given
      * expression.
      *
      * @param aFilterExpression
      * An expression to hide elements in the viewer.
      */
     public CoreExpressionFilter(Expression aFilterExpression) {
         filterExpression = aFilterExpression;
     }

     /*
      * (non-Javadoc)
      *
      * @see org.eclipse.jface.viewers.ViewerFilter#select(org.eclipse.jface.viewers.Viewer,
      * java.lang.Object, java.lang.Object)
      */
     public boolean select(Viewer viewer, Object parentElement, Object element) {

         try {
             return (filterExpression.evaluate(new EvaluationContext(null,
                     element)) != EvaluationResult.TRUE);
         } catch (CoreException e) {
             NavigatorPlugin.logError(0, e.getMessage(), e);
         }
         return true;
     }

 }

